Why is this in the flame zone?
I don't know, probably because a Marine runs the board.
I never served in the 75th Ranger Regiment, but as an Infantry Officer was expected to complete Ranger School, which by the grace of God, I managed to do without repeating a phase (the school is in three phases, a basic phase in Benning, where is mostly teaching, a mountain phase in Dahlonega, GA and a Swamp Phase in Eglin AFB in the Florida Panhandle).
You basically are on constant patrol in adverse terrain with constant missions coming in and the leadership of the patrol being graded. That would be tough enough (try climbing up and down the Tennessee Valley Divide with over 100 lbs of gear day after day), but to replicate combat stress, you are deprived of food and sleep and that just makes the experience miserable. I lost over 30 lbs in 62 days (I was in the shape of my life at the time. I would put my BMI at 21 or so, so it's not like I had a lot of weight to lose. By the end, we were basically metabolizing muscle and reeked of ammonia), and that was common. Most everyone went through periods of hallucinations from sleep deprivation. I'll never forget moving out on patrol at night and seeing one of my buddies w/ an AT-4 (disposable bazooka) strapped crossways across his backpack. I became convinced someone had become bisected and we were packing out his torso (w/ the AT-4 being his arms). I started freaking out, until my friend shook me out of it.
At any rate, 50% of the people who attempt the school never finish it. In my class, only about 20% of us managed to make it through without having to redo one of the three phases. That was luck on my part, I richly deserved to fail the last course as I was completely worthless by that point. My hands had cracked along the joints and I could barely use them.
Then to add the cherry on top of the "this sucks" cupcake, I went during the winter and it was fricking cold. I got a nasty case of trench foot on our last mission, which was a raid on Santa Rosa island in Pensacola Bay. We had to row zodiac boats to the Island, but the tide was miserable and we scuttled our boat on a sand bar about 100 meters out and had to jump out and drag it ashore.
As much as it sucked, it was, without a doubt, the best training I ever got in the Army (as far as preparing you for combat). I think if more people had the benefit of the training (it's closed off to everyone but males in combat arms units and Special Operations from other services (Force Recon, SEALs, etc)), there would be less causalities in combat.
At any rate, graduation was a very happy day for me. Though my future wife and parents didn't recognize me when they first saw me.